Alchemy in the series involves the transmutation of matter by understanding its structure, deconstructing it, and then reconstructing it into something new. Alchemists draw transmutation circles to perform this process, which serve as a medium to focus and channel energy. These circles are based on specific laws of nature, requiring both scientific knowledge and precise intent. The energy used in most alchemy comes from tectonic movement, drawing from the earth itself. However, this source is limited to those within Amestris and becomes a crucial plot point when the true origin of the national transmutation circle is revealed.

Some characters, such as Edward Elric, can perform alchemy without a transmutation circle. This ability is granted after seeing the Gate of Truth, a metaphysical gateway that represents ultimate knowledge. While the power it offers is great, it comes at a cost—usually a part of the alchemist’s body or soul. This idea reinforces the theme that power cannot be obtained without sacrifice.

Alchemy is contrasted with other forms of supernatural abilities in the series, such as the powers of the Homunculi. These beings, created through failed human transmutations, each possess regenerative abilities and unique traits linked to the seven deadly sins. Their powers do not follow the rules of Equivalent Exchange, reflecting their unnatural origins and often highlighting the dangers of circumventing natural laws.

The power system in Fullmetal Alchemist: Brotherhood is intricate and symbolic. It not only drives the action and world-building but also serves as a reflection of deeper themes such as consequence, balance, and the cost of ambition.